Existing tricycles, especially tricycles suitable for babies or children to ride, generally have a frame, a single-wheel assembly and a double-wheel assembly respectively disposed at the front end and the rear end of the frame, and a handlebar assembly matching with the single-wheel assembly to control steering. The single-wheel assembly comprises a steering wheel and pedals for driving the steering wheel to roll. The double-wheel assembly comprises two wheels and a supporting beam horizontally coupling the two wheels spaced apart. The tricycle may be ridden by controlling the handlebar assembly and pressing the pedals by feet. Since the supporting beam is relatively large, the two-wheel assembly usually occupies a relatively large space so that it is not convenient to carry/store the tricycle.